title: The role of reactive oxygen species and autophagy in safingol-induced cell death.
abstract: Safingol is a sphingolipid with promising anticancer potential, which is currently in phase I clinical trial. Yet, the underlying mechanisms of its action remain largely unknown. We reported here that safingol-induced primarily accidental necrotic cell death in MDA-MB-231 and HT-29 cells, as shown by the increase in the percentage of cells stained positive for 7-aminoactinomycin D, collapse of mitochondria membrane potential and depletion of intracellular ATP. Importantly, safingol treatment produced time- and concentration-dependent reactive oxygen species (ROS) generation. Autophagy was triggered following safingol treatment, as reflected by the formation of autophagosomes, acidic vacuoles, increased light chain 3-II and Atg biomarkers expression. Interestingly, scavenging ROS with N-acetyl-L-cysteine could prevent the autophagic features and reverse safingol-induced necrosis. Our data also suggested that autophagy was a cell repair mechanism, as suppression of autophagy by 3-methyladenine or bafilomycin A1 significantly augmented cell death on 2-5 μM safingol treatment. In addition, Bcl-xL and Bax might be involved in the regulation of safingol-induced autophagy. Finally, glucose uptake was shown to be inhibited by safingol treatment, which was associated with an increase in p-AMPK expression. Taken together, our data suggested that ROS was the mediator of safingol-induced cancer cell death, and autophagy is likely to be a mechanism triggered to repair damages from ROS generation on safingol treatment.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore.
authors.forename: L-U
authors.initials: LU
authors.lastname: Ling
authors.forename: K-B
authors.initials: KB
authors.lastname: Tan
authors.forename: H
authors.initials: H
authors.lastname: Lin
authors.forename: G N C
authors.initials: GN
authors.lastname: Chiu
mesh_terms: D001343:Autophagy / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002477:Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D013110:Sphingosine; C005682:safingol